1. Field of the Invention
The present invention relates to an apparatus for treating a substrate, and more particularly, to an electrostatic chuck and an apparatus for treating a substrate including the electrostatic chuck.
2. Discussion of the Related Art
In general, the fabricating process for a semiconductor device or a flat panel display device includes various steps. For example, there are a thin film deposition step for depositing a thin film on a substrate, an etching step for forming a photosensitive material pattern exposing or covering a desired portion of the thin film and etching the thin film using the photosensitive material pattern to form a desired thin pattern, an ion injection step for injecting ions into the desired portion and on the substrate, a cleaning step for removing impurities from the substrate and a detecting step for detecting defects of the thin pattern on the substrate. A wafer is used as the substrate for the semiconductor device. The above steps are processed in a chamber under an optimum condition.
In the fabricating process for the semiconductor device, an apparatus for treating the substrate, where a reaction gas, which is exited into a plasma state, is used for forming or etching a thin film on the substrate, is widely used. The apparatus for treating the substrate includes a chamber having a reaction space, a plasma electrode forming a plasma using a reaction gas, an electrostatic chuck supporting a substrate, and so on. The electrostatic chuck fixes the substrate thereon using an electrostatic power and heats the substrate to a processing temperature using a heater therein.
FIG. 1 is a schematic cross-sectional view of an apparatus for treating a substrate including an electrostatic chuck according to the related art, and FIG. 2 is a cross-sectional view of an electrostatic chuck according to the related art. FIG. 3 is a plan view of a heater in an electrostatic chuck according to the related art.
In FIGS. 1 and 2, the apparatus 10 includes a chamber 12 having a reaction chamber, an electrostatic chuck 16 disposed in the chamber 12, a gas distribution plate 18 over the electrostatic chuck 16, a gas providing pipe 20 providing a reaction gas into the gas distribution plate 18 and an exhaust pipe 22 through which the reaction gas and particles in the chamber 12 are exhausted. The reaction space of the chamber 12 is airtight from an outside. A substrate 14 is disposed on the electrostatic chuck 16. The reaction gas is sprayed from the gas distribution plate 18 onto the substrate 14 on the electrostatic chuck 16.
The electrostatic chuck 16 includes a body 24 of an aluminum-based material, an insulating plate 26 combined with and disposed on the body 24, a direct current electrode 28 and a heater 30 under the direct current electrode 28. The direct current electrode 28 and the heater 30 are disposed in the insulating plate 26. The insulating plate 26 is formed of a ceramic-based material. The body 24 includes a center portion 24a and an edge portion 24b having a thickness smaller than the center portion 24a such that the body 24 has a step difference. The edge portion 24b of the body 24 is combined with a focus ring 34. The focus ring 34 is formed of a ceramic-based material. A plasma region is expanded into an outer region of the substrate 14 due to the pocus ring 34 such that uniform plasma is deposited onto the substrate 14. The heater 30 includes an outer heater 42 and an inner heater 44.
The substrate 14 is disposed on the insulating plate 26 of the electrostatic chuck 16. The direct current electrode 28 of a tungsten-base material is connected to a direct current source 36 such that an electrostatic power is generated. The substrate 14 is stably fixed on the electrostatic chuck 16 by the electrostatic power. A radio frequency (RF) power source 38 is connected to the body 24 of the electrostatic chuck 16, and the chamber 12 is connected to a ground. As a result, the body 24 of the electrostatic chuck 16 is electrically insulated from the chamber 12. A matcher 40 matching impedances for providing a maximum power is disposed between the RF power source 38 and the body 24 of the electrostatic chuck 16.
Referring to FIG. 3, the heater 30 having a coil shape is disposed in the electrostatic chuck 16. The inner heater 44 is disposed inside of the outer heater 42. When a thin film is deposited onto the substrate 14 or a thin film on the substrate 14 is etched, the substrate 14 is heated into a process temperature by the heater 30.
The apparatus 10 including the above-mentioned electrostatic chuck 16 is driven as followings. First, the substrate 14 is transported into the chamber 12 through a door (not shown) and disposed onto the insulating plate 26 of the electrostatic chuck 16. Then, the substrate 14 is stably fixed onto the insulating plate 26 by an electrostatic power generated by the direct current electrode 28. Gases in the reaction space of the chamber 12 are exhausted such that the reaction space of the chamber 12 has a vacuum state. A reaction gas is sprayed over the substrate 14 through the gas distribution plate 18, and an RF power is applied into the electrostatic chuck 16 by the RF power source 40 at the same time. An RF electric field is generated between the electrostatic chuck 16 and the chamber 12 by the RF power applied into the electrostatic chuck 16. An accelerated electron by the RF electric field is collided with a neutral gas such that a plasma including an ion and a radical is generated. As a result, a thin film is deposited onto the substrate 14 or a thin film on the substrate 14 is etched.
As mentioned above, the substrate 14 is heated into a process temperature by the heater 30 in the body 24 of the electrostatic chuck 16. The outer and inner heaters 42 and 44 are independently driven such that a temperature in the center portion of the electrostatic chuck 16 and a temperature in the edge portion of the electrostatic chuck 16 can be independently controlled. However, since the heater 30 is closet to a top surface of the insulating plate 26 and the ceramic material of the insulating plate 26 has a relatively low thermal conductivity, it is difficult to uniformly control a temperature on the top surface of the insulating plate 26. Accordingly, the electrostatic chuck 16 has a temperature deviation at a top surface of the electrostatic chuck 16. In addition, the temperature deviation is caused by a coil pattern of the heater 30. Since the temperature deviation causes a bad effect on a deposition process of a thin film onto the substrate 14 or an etching process of a thin film on the substrate 14, the products has a deteriorated quality because of the temperature deviation.